Wood particle board containing vermiculite and method of making same



5, 1969 A. KAWAM 3,459,629

WOOD PARTICLE BOARD CONTAINING VERMICULITE AND METHOD OF MAKING SAME Filed July 1, 1966 -r INVENTOR ANTOINE KAWAM BY /W ATTORNEY Unite States Patent 3 459,629 WOOD PARTICLE BbARD CONTAINING VER- MICULITE AND METHOD OF MAKING SAME Antoine Kawam, Silver Spring, Md., assignor to W. R.

Grace & Co., New York, N.Y., a corporation of 5 Connecticut Filed July 1, 1966, Ser. No. 562,195 Int. Cl. B32b 5/16, 13/12, 19/04 US. Cl. 161--163 6 Claims This invention relates to fire resistant building materials. In one particular aspect it relates to composite fire resistant vermiculite-wood boards.

There is a need for improved, strong, light weight fire resistant composite boards. These boards are normally prepared by bonding individual wood particles or chips with various binders. Many of the commercial uses require a high degree of fire resistance, which is usually achieved by blending various additives such as borates, phosphates and the like with the wood particles.

Exfoliated vermiculite, because it is readily available and possesses a high degree of thermal resistance has been laminated on the surface of the boards.

However, composite boards made from blends of exfoliated vermiculite-wood chips have not given the fire retardation and strength anticipated. Exfoliated vermiculite has proven very difiicult to blend with wood particles and fire propagation takes place through the interconnected wood particles. Attempts to coat the wood particles with fine ground exfoliated vermiculate and thus insulate them from flame propagation have proven extremely difficult and economically unfeasible. Also exfoliated vermiculite, possessing very low strength in itself, results in a weak composite board.

It is therefore an object of this invention to provide a fire-resistant composite board containing wood particles in which the particles are protected from the destructive effects of fire and heat. This and other objects of the invention will become apparent from the following detailed description and specific examples.

Broadly, this invention provides a composite board, comprising a particle board consisting of a mixture of wood particles, and a raw unexpanded vermiculite ore bonded with a suitable binder.

Commercial vermiculite ore is designated by grades and is marketed as Grades l-5. The U8. series size of these grades are as follows: Grade 1, 3-12; Grade 2, 8-16; Grade 3, 1240; Grade 4, 30-70; and Grade 5, 40.

Any of these grades of verirnculite ore is applicable to this invention. It is to be understood that where the term unexpanded vermiculite ore is used it means an expandable or exfoliated ore.

The wood particles may be in the form of a chip, flake, exclesior, shaving, splinter or sawdust made by grinding tearing, and cutting debarked wood.

The ratio of unexpanded vermiculite ore to wood chips depends upon the end use. The higher the vermiculite ore content, the better the heat and fire rating, but the weaker the final structure will be. For applications where structural strength is not required but a high fire resistance is necessary, a higher ratio of vermiculite ore to wood chips can be used. The vermiculite ore content can vary from 10 to 80% based on the weight of the wood chips, with 25% ore and 75% wood suitable for most purposes.

The type of binder and the amount necessary will depend upon the particular use for which the product is intended.

The preferred binders of this invention are those commonly used in particle board preparation; namely, urea formaldehyde, phenol formaldehyde, and to a minor degree milamin-HCHO, and other aminoblasts.

Other additives such as paraffin based wax emulsions can be added to the vermiculite ore-wood chips where sizing is necessary.

It is also within the scope of this invention to use other fire resistant expandable minerals such as perlite and the like.

The uses to which the composite board of this invention can be applied are extremely varied. Among the uses deemed within the scope of the invention are wallboards, sound insulations, heat isulations, decorative panels, table covers, roofing, insulating panels for appliances, acoustical tile, backing for decorative wood paneling, materials for doors, underlayments, insulations in safes and the like.

In one method of carrying out the invention, exfoliated vermiculite coated with adhesive is spread out on the bottom of a suitable mold. A layer of unexpanded vermiculite ore, also coated with adhesive, is spread upon the exfoliated vermiculite ore wood chips and a binder is spread upon the unexpanded vermiculite ore layer to form a mat. If desired, after the mat of wood chips and vermiculite ore has been built up, a layer of unexpanded vermiculite ore coated with adhesive may be applied to the mattress layer and a further layer of exfoliated vermiculite, also coated with adhesive, can be applied to the vermiculite ore layer. The assembly is subjected to heat and compression in the usual way to form a board provided on both sides with fire proof layers of exfoliated vermiculite and vermiculite ore and having a center core of Wood chips and vermiculite ore. This laminated board is illustrated in the drawing. It shows the board generally at 10, the facing layers of exfoliated vermiculite at 11 and 12, the unexpanded vermiculite ore layer at 13 and 14, and the center core of vermiculite ore wood chips and binder at 15.

The invention is illustrated but not limited by the following specific examples.

EXAMPLE I 1500 grams of wood chips inch x A inch) having a moisture content of 7.2%, and 500 grams of No. 3 unexpanded vermiculite ore were blended together. During the blending, 41.5 grams of a 45% paraflin base wax emulsion was added to the mix in the form of a fine atomizing jet. After adding the wax, 230 grams of urea formaldehyde adhesive containing 65% solids was added. The moisture content of the composite was them 10.5%.

1760 grams of the composite was spread evenly in the bottom of a 14 inch square mold forming a mat of approximately 5 inches in height. The mat was then compressed to a thickness of approximately 1 /2 inches in a cold press.

The mat was removed from the mold and pressed at 35 ton pressure and 300 F. to inch thickness. The pressure was then lowered to 12 tons and maintained in that condition for 3 minutes. A 4 inch board resulted.

This board exhibited excellent fire resistance and the vermiculite ore particles upon contact with a flame, or when submitted to intense heat, expanded and prevented fire propagation.

EXAMPLE II A board was prepared as described in Example I, but in place of the unexpanded vermiculite ore, unexpanded perlite was used. This board also exhibited excellent fire 3 resistance and the perlite ore particles upon contact with a flame or submitted to intense heat, expanded and prevented fire propagation.

EXAMPLE III Two boards were prepared, (1) 3000 grams of wood chips (moisture content 7.2%) and 100 grams of unexpanded vermiculite ore No. 3 were blended together. During the blending, 83 grams of a 45% paraffin based wax emulsion was sprayed upon the tumbling mass. 460 grams of urea formaldehyde resin adhesive containing 65% solids was added to the wood chip vermiculite ore mix. The total water content of the composite was 400 grams of expanded No. 2 vermiculite ore was blended with 74 grams of urea formaldehyde adhesive and 9 grams of a 45 parafiin based wax emulsion.

200 grams of the vermiculite ore urea-formaldehyde resin material was spread evenly on the bottom of a 14 inch square mold. The height of this layer was approximately /2 inch. 1725 grams of the wood chip-vermiculite ore composite was spread evenly on the top of the ore layer, forming a mat of approximately 5 inches in height. 200 grams of the vermiculite ore resin mix was spread evenly on the mat layer, to a height of approximately /2 inch. The three layers were then compressed to a thickness of approximately 2 inches in a cold press.

The composition was placed in apress at 300 F. and tons pressure for 3 minutes and compressed to inch thickness, at which time the pressure was dropped to 12 tons and held for an additional 3 minutes. A inch composite board resulted.

(2) The second board was prepared by blending 4000 grams of food chips, 83 grams of a paraffin base wax emulsion, and 460 grams of 65 solution of ureaformaldehyde resin adhesive and 9 grams of wax emulsion.

200 grams of the vermiculite ore urea-formaldehyde resin composite was spread evenly in the bottom of a 14 inch square mold to a height of approximately /2 inch. Then 1725 grams of the wood chip resin was spread evenly on top of the vermiculite layer to a height of approximately 5 inches. This was followed by another 200 grams of the vermiculite to form additional /2 inch layer. The entire composite was compressed to a thickness of approximately 2 inches in a cold press. It was then placed in a press of 350 F. at 300 tons pressure for 3 minutes and compressed to a 4 inch thickness, at which time the pressure dropped to 12 tons and held for an additional 3 minutes. A /2 inch composite board resulted.

The difference then between both boards is that the first board contains a center core of wood chips and unexpanded vermiculite ore with surface layers of exfoliated vermiculite, while the second board contains a core of only wood chips and resin with similar surface layers of exfoliated vermiculite.

Both boards were subjected to the hot flame of the tip of an acetylene torch. In board (1) which is the board of this invention, no burning or propagation of the flame occurred. After 3 minutes exposure of one side of this board to flame, the other side remained cool to the touch. Damage to the exposed face was only superficial and confined to the area of direct contact. The second board (2) which is similar to the prior art compositions started to char, burn and smoke after 80 seconds of exposure to the flame. These tests show the remarkable and unobvious retardation properties of a board prepared according to the method of this invention.

EXAMPLE IV 3000 grams of wood chips and 1000 grams of No. 3 unexpanded vermiculite ore were blended together and sprayed with 82 grams of a 45 paraffin wax base emul- 4 sion. 460 grams of a 65% urea-formaldehyde adhesiv was added to the mix.

2000 grams of unexpanded No. 4 vermiculite ore was blended with 286 grams of a 65 urea formaldehlyde resin adhesive and 4.15 grams of paraffin was emulsion.

A board was then prepared by spreading evenly 745 grams of the ore adhesive mix on the bottom of a 14 inch square mold and then applying 1600 grams of the wood chip vermiculite and ore composite on top of it and following this by additional layer of 745 grams of the vermiculite ore and formaldehyde resin. This three layered composite was then compressed to 2 inches in a cold press after which it was subjected to 35 tons pressure at 3 minutes at 300 F. and compressed to inch thickness. The pressure was then dropped to 12 tons for an additional 3 minutes. The resulting board was /51 inch.

A second board was prepared as the first, differing in that it contained a surface layer of vermiculite ore on only one side. Both boards were subjected to the hot flame of the tip of an acetylene torch and exhibited excellent fire and heat resistance.

EXAMPLE V A special product board can be prepared where unusually high fire resistance is required as on ships, airplanes, safes, etc.

A five layered composite board was prepared containing the center layer or core 1200 grams of wood chips and 400 grams of No. 3 expanded vermiculite ore blended with 128 grams of urea formaldehyde resin and 16 grams of paraffin base wax. On either side of the core layer was a layer of unexpanded No. 3 vermiculite ore consisting of 300 grams of the ore, 24 grams of urea formaldehyde resin, and 3 grams of the paraflin base wax. The surface layers were exfoliated vermiculite and contained 200 grams of the vermiculite, 16 grams of urea formladehyde resin and 2 grams of paraffin base wax. This board was prepared using the method described in the previous examples. The resulting board is illustrated in the drawing.

The board was exposed for 10 minutes to the hot tip of an acetylene torch and exhibited only minor localized effect. The side opposite the torch reached a temperature of to F. No burning, smoking or charring was exhibited on the flame side.

I claim:

1. A particle board consisting of a mixture of wood particles and unexpanded vermiculite ore bonded with a suitable binder.

2. A composite board, comprising the particle board of claim 1 and having on at least one side of said particle board a layer of compressed exfoliated vermiculite integral therewith.

3. A composite board, comprising the particle board of claim 1 and having on at least one side of said particle board a layer of unexpanded vermiculite ore integral therewith.

4. A composite board, comprising a particle board of claim 1 and having on at least one side of said particle board, two layers, the first layer being unexpanded vermiculite ore integral with said board, and the second layer being exfoliated vermiculite integral with said first layer.

5. A method of making a composite board, comprising the steps of spreading a mixture of exfoliated vermiculite and synthetic resin on the bottom half of pressing means in which the board is to be prepared, spreading on such layer a mattress of wood chips and unexpanded vermiculite ore mixed with a synthetic resin binder, spreading on the mattress of wood chips and unexpanded vermiculite ore a further layer of exfoliated vermiculite and synthetic resin, and subjecting the three layers to heat and pressure thereby to form a composite board with two integral layers of exfoliated vermiculite.

5 6 6. A particle board consisting of a mixture of wood ROBERT F. BURNETT, Primary Examiner gagi-iglfiadgd unexpanded perlite ore bonded with a suit- WILLIAM L VAN BALEN, A S Si stant Examiner References Cited U s,c1 X,R. UNITED STATES PATENTS 5 161-162, 168, 171, 208, 261; 264--113 2,390,732 12/1945 Page 161-163 3,109,767 11/1963 Polovtsefi et a1 161-163 

1. A PARTICLE BOARD CONSISTING OF A MIXTURE OF WOOD PARTICLES AND UNEXPANDED VERMICULITE ORE BONDED WITH A SUITABLE BINDER. 